From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Date: Fri, 26 Mar 2010 21:35:34 +0100
Thread-Topic: Question about ground impedance at 8.97 KHZ  Stefan.
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Subject: LF: RE: Question about ground impedance at 8.97 KHZ  Stefan.
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Paul,

I believe that Marcus reported a loss resistance ("ground loss") of about=
 1 kOhm.
For Stefan: based on 250W/0.48A the total loss resistance should be 1085=
 Ohm. The coil (553mH, Q=3D82) counts for 380 Ohm, so "ground loss" is abo=
ut 700 Ohm.
So unless you are living on solid rock or in a desert 70 kOhm seem very hi=
gh.
Do you know the loss on 137kHz ? I guess that on 10kHz it will be 20 to 50=
 times more.

73, Rik  ON7YD - OR7T

________________________________________
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or=
g] namens Paul A. Cianciolo [paulc@snet.net]
Verzonden: vrijdag 26 maart 2010 19:38
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: LF: Question about ground impedance at 8.97 KHZ  Stefan.

Hello All,

Below is a quote from the Stefan's web page concerning his latest "Dreamer=
s Band" DX contact Congratulations again Stefan.
>From this information alone is it possible to calculate or know the antenn=
a system impedance.




"100m Vertical wire antenna, coil/antenna voltage was abt 15kV rms, averag=
e antenna current about 480mA, giving up to 1,7mW ERP. Applied power was=
 up to 250W."

Pertaining to the coil "Technical and mechanical data: L=3D553mH, Q=3D82,=
 R(DC)=3D283 Ohm; 0,4mm diameter enameled copper wire, about 1200 turns!=
 Average diameter 0,55m, height abt 0,5m. So, about 2000m wire! :-)"



I have built a small impedance bridge that operates at 10 KHZ and shows my=
 sloping 170' wire as 70K Ohms. I can also see approx 500 PF that can be=
 nulled out using the bridge?

Can the 70K value possibly be correct?   (3) 6' ground rods about 6' apart=
 are the ground... plus the electrical ground of the house.

I am hoping to attempt a local transmission on 9KHZ

Any information would be helpful.

Thank you

Paul

W1VLF